双作用式节流截止阀主要由喷嘴、柱塞形阀芯、（）、阀体、阀杆等组成.
A.节流轴
B.节流套
C.节流孔
D.节流件
参考答案：A
Our class teacher is still on ______ holiday, so our monitor will be in ______ charge of the meeting today.
A．/; /
B．the; the
C．a; /
D．the; a
急性扁桃体炎并发症有哪些？
